This invention relates to an electrically conducting plastics complex material endowed with higher than a certain value of electrical conductivity without inclusion of metallic contents and more particularly to such electrically conductive plastic complex material suitably used in conjunction with electrical, electronic or electrochemical devices such as metal-halogen batteries.
Recently, the use of the electrically conductive plastic complex material has become widespread not only in electrical devices for domestic use but as computer components or electrodes for recently developed metal-halogen batteries.
These electrically conductive plastic complex materials are used as so-called molded pieces or synthetic resin paint and are usually manufactured by dispersing fine powders of Ag, Cu, Al or the like metals or fine carbon particles into the synthetic resin. Since the electrically conductive plastic complex materials are prepared by simply dispersing electrically conductive substances into the non-conductive plastic material, their electrical conductivity may be fluctuated widely by non-homogeneous dispersion of the conductive particles. In addition, it has not been possible to increase the electrical conductivity beyond a certain limit although some electrically conductive complex with contents of the dispersed metallic powders exhibits an electrical conductivity of the order of 10.sup.4 to 10.sup.5 ohm.sup.-1 cm.sup.-1. The result is unavoidable limitations on the application of the electrically conductive plastic complex material.
Recently, it has been proposed to make use of certain dopants that may affect polyacetylene, polypyrrole or polyparaphenylene sulfide so as to make them electrical conductivity. However, the resulting material tends to be unstable in physical properties and the apparatus for producing it is also complicated in structure.
In general, the insulating materials such as plastics, semi-conductors such as Ge, Si, carbon black or graphite or conductors such as metal have intrinsic volume resistivity proper to them.
The volume resistivity for the insulating material is higher than 10.sup.8 ohm-cm, while that for semiconductors is 10.sup.-3 to 10.sup.8 ohm-cm and that for conductors is less than 10.sup.-3 ohm-cm.
The volume resistivity of these electrical materials change in accordance with variation of temperature.
Thus, the volume resistivity of the insulating material generally decrease with rise in temperature, while that of the semiconductors and that of conductors increase with rise in temperature. An electrically conductive complex material obtained by mixing carbon black into the base polymer and kneading them together is lightweight and low in cost while also exhibiting good workability. Hence, it is employed in a variety of electrical devices. However, the volume resistivity of this material also tends to increase with rise in temperature.
The result is that the electrical or electronic devices which make use of the carbon black mixed into the base polymer material undergo changes in their properties in accordance with variation of temperature and hence are not capable of keeping constant properties.